PersistentDataBlockManager.java revision 74e9b18b2de2127e081b170cdd4622193cfb7543 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.service.persistentdata;
18
19import android.annotation.SystemApi;
20import android.annotation.IntDef;
21import android.os.RemoteException;
22import android.util.Slog;
23
24import java.lang.annotation.Retention;
25import java.lang.annotation.RetentionPolicy;
26
27/**
28 * Interface for reading and writing data blocks to a persistent partition.
29 *
30 * Allows writing one block at a time. Namely, each time
31 * {@link PersistentDataBlockManager#write(byte[])}
32 * is called, it will overwite the data that was previously written on the block.
33 *
34 * Clients can query the size of the currently written block via
35 * {@link PersistentDataBlockManager#getDataBlockSize()}.
36 *
37 * Clients can query the maximum size for a block via
38 * {@link PersistentDataBlockManager#getMaximumDataBlockSize()}
39 *
40 * Clients can read the currently written block by invoking
41 * {@link PersistentDataBlockManager#read()}.
42 *
43 * @hide
44 */
45@SystemApi
46public class PersistentDataBlockManager {
47    private static final String TAG = PersistentDataBlockManager.class.getSimpleName();
48    private IPersistentDataBlockService sService;
49
50    /**
51     * Indicates that the device's bootloader lock state is UNKNOWN.
52     */
53    public static final int FLASH_LOCK_UNKNOWN = -1;
54    /**
55     * Indicates that the device's bootloader is UNLOCKED.
56     */
57    public static final int FLASH_LOCK_UNLOCKED = 0;
58    /**
59     * Indicates that the device's bootloader is LOCKED.
60     */
61    public static final int FLASH_LOCK_LOCKED = 1;
62
63    @IntDef({
64        FLASH_LOCK_UNKNOWN,
65        FLASH_LOCK_LOCKED,
66        FLASH_LOCK_UNLOCKED,
67    })
68    @Retention(RetentionPolicy.SOURCE)
69    public @interface FlashLockState {}
70
71    public PersistentDataBlockManager(IPersistentDataBlockService service) {
72        sService = service;
73    }
74
75    /**
76     * Writes {@code data} to the persistent partition. Previously written data
77     * will be overwritten. This data will persist across factory resets.
78     *
79     * Returns the number of bytes written or -1 on error. If the block is too big
80     * to fit on the partition, returns -MAX_BLOCK_SIZE.
81     *
82     * @param data the data to write
83     */
84    public int write(byte[] data) {
85        try {
86            return sService.write(data);
87        } catch (RemoteException e) {
88            onError("writing data");
89            return -1;
90        }
91    }
92
93    /**
94     * Returns the data block stored on the persistent partition.
95     */
96    public byte[] read() {
97        try {
98            return sService.read();
99        } catch (RemoteException e) {
100            onError("reading data");
101            return null;
102        }
103    }
104
105    /**
106     * Retrieves the size of the block currently written to the persistent partition.
107     *
108     * Return -1 on error.
109     */
110    public int getDataBlockSize() {
111        try {
112            return sService.getDataBlockSize();
113        } catch (RemoteException e) {
114            onError("getting data block size");
115            return -1;
116        }
117    }
118
119    /**
120     * Retrieves the maximum size allowed for a data block.
121     *
122     * Returns -1 on error.
123     */
124    public long getMaximumDataBlockSize() {
125        try {
126            return sService.getMaximumDataBlockSize();
127        } catch (RemoteException e) {
128            onError("getting maximum data block size");
129            return -1;
130        }
131    }
132
133    /**
134     * Zeroes the previously written block in its entirety. Calling this method
135     * will erase all data written to the persistent data partition.
136     */
137    public void wipe() {
138        try {
139            sService.wipe();
140        } catch (RemoteException e) {
141            onError("wiping persistent partition");
142        }
143    }
144
145    /**
146     * Writes a byte enabling or disabling the ability to "OEM unlock" the device.
147     */
148    public void setOemUnlockEnabled(boolean enabled) {
149        try {
150            sService.setOemUnlockEnabled(enabled);
151        } catch (RemoteException e) {
152            onError("setting OEM unlock enabled to " + enabled);
153        }
154    }
155
156    /**
157     * Returns whether or not "OEM unlock" is enabled or disabled on this device.
158     */
159    public boolean getOemUnlockEnabled() {
160        try {
161            return sService.getOemUnlockEnabled();
162        } catch (RemoteException e) {
163            onError("getting OEM unlock enabled bit");
164            return false;
165        }
166    }
167
168    /**
169     * Retrieves available information about this device's flash lock state.
170     *
171     * @return FLASH_LOCK_STATE_LOCKED if device bootloader is locked,
172     * FLASH_LOCK_STATE_UNLOCKED if device bootloader is unlocked,
173     * or FLASH_LOCK_STATE unknown if this information cannot be ascertained
174     * on this device.
175     */
176    @FlashLockState
177    public int getFlashLockState() {
178        try {
179            return sService.getFlashLockState();
180        } catch (RemoteException e) {
181            onError("getting flash lock state");
182            return FLASH_LOCK_UNKNOWN;
183        }
184    }
185
186    private void onError(String msg) {
187        Slog.v(TAG, "Remote exception while " + msg);
188    }
189}
190